Sender: <marv@lancaironline.net>
To:  lml@lancaironline.net
Date: Sun, 27 Jan 2013 20:47:53 -0500
Message-ID: <redirect-6032173@logan.com>
Received-SPF: none
 receiver=logan.com; client-ip=209.86.89.63; envelope-from=colyncase@earthlink.net
DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws;
  s=dk20050327; d=earthlink.net;
  b=Mz4wNc4qmsRZv6cObqI6OOb/3bZE8uGoHQSUaA72mjGItNTDDEyJCTLo6GQcFfwc;
  h=Received:Content-Type:Mime-Version:Subject:From:In-Reply-To:Date:Content-Transfer-Encoding:Message-Id:References:To:X-Mailer:X-ELNK-Trace:X-Originating-IP;
Content-Type: text/plain; charset=us-ascii
Mime-Version: 1.0 (Apple Message framework v1085)
Subject: Re: [LML] Also, does the Primer work?
From: Colyn Case <colyncase@earthlink.net>
In-Reply-To: <list-6031892@logan.com>
Content-Transfer-Encoding: quoted-printable
References: <list-6031892@logan.com>

George,   I don't have the whole answer but maybe one of the engine =
experts will chime in.
I do know:
- engine pump does have a spring loaded bypass so that the boost pump =
can drive fuel through it if it fails.  (We learned that at the =
Continental Factory course this week).
- High boost is a speed function on the boost pump.  I have never seen a =
IV that didn't have one.
- I'm not sure what the primer button does (I have both) but I think it =
has special plumbing.   Many planes don't have this.
- I need to do some research to understand the relative outputs of the =
engine pump vs. the boost pump and how that will affect mixture in the =
event of an engine pump failure.   My expectation is low boost will not =
be enough and high boost will probably require a mixture adjustment.

On Jan 27, 2013, at 12:30 PM, George Wehrung wrote:

As a continuation to my previous post, referencing the build manual =
chapters 14 and 23:

Chapter 23: wiring:  denotes a Single Pole Double Throw rocker switch =
for the LOW-OFF-HIGH positions of the fuel boost pump.

Chapter 14: Firewall Forward, depicting the fuel flow does not show a =
separate routing for the fuel primer circuit.  So how does the primer =
function work?  Is it merely pushing a higher volume of fuel through the =
circuit?  I know it's necessary for hot starts to quickly circulate the =
cooler fuel to the manifold but does it somehow bypass the gascolator =
and the engine driven fuel pump?  This would make sense if it did as =
some aircraft call for pushing in the primer and possibly holding it in =
to keep the engine running in the event of an engine driven fuel pump =
failure.

So then why do I only have a low selection of the boost pump?  Should I =
replace my boost pump switch with a three-position LOW-OFF-HIGH switch.  =
Should I have the boost pump on LOW for takeoff, descent and landing?

Thanks again

George


--
For archives and unsub =
http://mail.lancaironline.net:81/lists/lml/List.html